Absorption of laser radiation in ultracold plasma

In this paper, we analyze the spectral behavior(optical thickness, shape and linewidth) of laser radiation absorption under the correlation heating of ions in an ultracold plasma. The Voigt formula is used to find the absorption coefficient.The spectral line width is shown to grow with time while the optical thickness reduces. Our modeling results are in good agreement with the experimental findings reported in the literature.

IMPROVEMENT ON FATIGUE LIFE OF ALLOY LY12CZ AFTER LASER RADIATION AND ITS DAMAGE EVOLUTION

The change of microstructure of fatigue specimens before and after laser radiation was studied by transmission electron microscopy.The results show that the diameter of dislocation cell λ tends to a constant at fatigue failure.Based on the principles of continuous damage mechanics,expressions of the fatigue damage criterion and processes of fatigue damage evolu- tion for L Y12CZ have been derived.

Application of Well-Known Antiviral Drugs in the Field Formed by the Unexplained Properties of Low-Level Laser Radiation in Therapy of Covid-19 and Chronic Viral Hepatitis

Low-level laser therapy (LLLT) or cold laser has been used in medicine for several decades. However, the method utilizes a direct contact of the light beam with a patient. Further research resulted in development of another method that enables remote transmission of the pharmacological properties of a medicament into a human body with the application of low-level laser radiation as the light source. 18 patients with different viral diseases were treated with the antiviral drugs placed into the field formed by the unexplained properties of low-level laser radiation of the “device for transfer of the pharmacological properties of a drug into the patient’s body”. This resulted in improvement of the patient’s condition, the absence of side effects and adverse reactions when using drugs in the proposed device and shortened therapy period for patients with chronic hepatitis C infection and Covid-19 patients. The long-term follow-up of the patients with chronic hepatitis B infection showed that hepatitis B virus remained at low replication levels under the influence of the therapy, which made it possible to avoid such formidable complications of the disease as cirrhosis of the liver and liver cancer.

Electron-Cyclotron Laser Using Free-Electron Two-Quantum Stark Radiation in a Strong Uniform Axial Magnetic Field and an Alternating Axial Electric Field in a Voltage-Supplied Pill-Box Cavity

We consider the radiation from the beam electrons traveling in a strong uniform axial magnetic field and an axial alternating electric field of wavelength Aw generated by a voltage-supplied pill-box cavity. The beam electrons emit genuine laser radiation that propagates only in the axial direction through free-electron two- quantum Stark radiation. We find that laser radiation takes place only at the expense of the axial kinetic energy when Aw 〈〈 c/（ωc/γ）, where ωc/γ is the relativistic electron--cyclotron frequency. We formulate the laser power based on quantum-wiggler electrodynamics, and envision a laser of length lore with estimated power 0.1 GW/（kA） in the 10-4 cm wavelength range.

Theoretical and experimental studies on high-power laser-induced thermal blooming effect in chamber with different gases

High-power laser induced thermal blooming effects in a closed chamber with three different gases are investigated theoretically and experimentally in this work. In the theoretical treatment, an incompressible gas turbulent model is adopted.In the numerical simulation the gas refractive index as a function of both the temperature and pressure is taken into consideration. In the experimental study the pump-probe technology is adopted. A high-power 1064-nm fiber laser with maximum output power of 12 k W is used to drive the gas thermal blooming, and a 50-m W high-beam-quality 637-nm laser diode(LD)is used as a probe beam. The influences of the gas thermal blooming in the chamber on the probe beam wavefront and beam quality are analyzed for three different gases of air, nitrogen, and helium, respectively. The results indicate that nitrogen is well suitable for restraining thermal blooming effect for high-power laser. The measured data are in good agreement with the simulated results.

Materials Response to High Power Energy Lasers(A Short Course—Part II)

With recent attention to high power energy and its interaction with materials of different types,both in industry and military application,this paper covers a short review course into subject of materials response in respect to such high power energy lasers.In this paper,we are covering laser interaction with solid and going through steps of phase changes,from solid to liquid and finally vapor stage.As we indicated in this part of short course mainly Part I,we have stated of series of article on the subject of Materials Responses to High Power Energy Lasers and continue these series by starting to introduce the Laser Light Propagation either in vacuum or through atmosphere by also introducing thermal blooming effects as well,then we cover,subjects such as Optical Reflectivity,thermal responses of materials by looking at Latent Heat of Fusion as well as Vaporization,No Phase Changes in both Semi-Infinite Solid or Slab of Finite Thickness,Melting and Vaporization and then move on to Effects of Pulsed or Continuous Laser Radiation as well,throughout of next few parts that we report them as further Short Courses content.

Materials Response to High Power Energy Lasers (A Short Course-Part III)

With recent attention to high power energy and its interaction with materials of different type,both in industry and military application,this paper covers a short review course into subject of materials response in respect to such high power energy lasers.In this paper,we are covering laser interaction with solid and going through steps of phase changes,from solid to liquid and finally vapor stage.As we indicated in this part of short course mainly Part I and Part II,we have started a series of articles on the subject of Materials Responses to High Power Energy Lasers and continue these series by starting to introduce the Laser Light Propagation into materials.In this part namely Part III,we are discussing,one of the most important effects of intense laser irradiation is the conversion of the optical energy in the beam into thermal energy in the material.This is the basis of many applications of lasers,such as welding and cutting.We shall summarize here this thermal response.It is basically a classical problem,namely heat flow,in a usual manner of heat conduction,we show solutions to the equation which governs the flow of heat and discuss change of phases in targeting material from solid to liquid and finally vapor and plasma stages step by step.

Materials Response to High Power Energy Lasers(A Short Course—Part I)

With recent attention to high power energy and its interaction with materials of different type,both in industry and military application,this paper covers a short review course into subject of materials response in respect to such high power energy lasers.In this paper,we are covering laser interaction with solid and going through steps of phase changes,from solid to liquid and finally vapor stage.We describe the radiation wave,propagation wave in a complex form solution,utilizing Maxwell’s equation within dielectric materials,then we look at compression of materials,due to melting and boiling driven by heat transfer energy radiation and conduction induced by these high power energy lasers such is Nd Ya and CO2 lasers with wavelengths anywhere from 1.6μm to 10.6μm.We also look at Hugoniot Elastic Limit(HEL)and spall strength of materials,with the energy lasers dueling with targeted material,where also,physics of hydrodynamics effects due to strong shock is involved.We also talk about certain available computer that allows end user to calculate these phenomena in 1-D to 3-D type scenarios.Although covering all these above issues that are very lengthy write-up proposition,we have tried to be very brief,yet to the point presentation in form of a short course in this paper.

Materials Response to High Power Energy Lasers(A Short Course—PartⅣ)

A complete understanding of laser interaction with materials is still a matter of trials and adjustments.The real physical processes of laser beam interaction(drilling,cutting,welding,or being used as a directed energy weapon application)with materials are very complex.Problem of laser interaction with materials presents many difficulties,both from modeling as well as from experimental sides.One would expect a reasonable description of the main phenomena occurring during laser interaction,but this is complicated because many of physical processes equally contribute to the development of conservation equations,producing drawback because of a great complexity of the equations to be solved.In most instances,this leads to formulation of a model needed to be solved numerically.A lack of pertinent experimental data to compare with,forces one to simplify some equations and use previous analytical and computational work done in this field.In Part IV here,we cover the absorption coefficient,which can be derived from the material’s dielectric function and conductivity,determines the absorption of light as a function of depth.However,the specific mechanisms by which the absorption occurs will depend on the type of material.In general,photons will couple into the available electronic or vibrational states in the material depending on the photon energy.In insulators and semiconductors,the absorption of laser light predominantly occurs through resonant excitations such as transitions of valence band electrons to the conduction band(inter-band transitions)or within bands(inter-sub-band transitions).In this part we cover all the aspect of the“Mathematical of Laser Absorption in Metals”that fits into this part of our suggesting short courses in different parts so far.

Theoretical Study of Laser Emission for C-Like (Ar XIII), (Ti XVII) and (Fe XXI)

Energy levels, transition probability and oscillator strengths have been calculated for the Ar XIII, Ti XVII and Fe XXI. The configurations included in the calculations are 2s2 2p2, 2s2 2p 3l (l = s, p & d) and 4l (l = s, p, d, & f) of C-like Ar XIII, Ti XVII & Fe XXI which has 69 fine structures by using the fully relativistic flexible atomic code (FAC) program. These data are used in the determination of the reduced population and gain coefficients over a wide range of electron densities from (10+18 to 10+23) and at various plasmas temperatures. The results show that the transitions in Ar18+, Ti22+, and Fe26+ ions are the most promising laser emission lines in the XUV and soft X-ray spectral regions.

Continued Study on Hohlraum Radiation Source with Approximately Constant Radiation Temperature

An experiment was performed on the Shenguang III prototype laser facility to continue the study on hohlraum radiation source with approximately constant radiation temperature using a continuously shaped laser pulse.A radiation source with a flattop temperature of about130 e V that lasted about 5 ns was obtained.The previous analytical iteration method based on power balance and self-similar solution of ablation was modified taking into account the plasma movements and it was used to design the laser pulse shape for experiment.A comparison between experimental results and simulation is presented and better agreement was achieved using the modified method.Further improvements are discussed.

Editorial for Special Issue on Multiphoton Processes

With the rapid development of ultrafast intense laser technologies, the interaction of intense laser radiation with mat- ter has been a frontier for few decades. The International Conference on Multiphoton Processes （ICOMP）, initiated in 1977, covers the latest advances in the field every three years. The special issue is based on the spirit of the 13th International Conference on Multi-Photon Processes, ICOMP13, which was held in Shanghai, organized by Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, on Dec. 7-10, 2014